When Everything Turns To Black
by JuliaShumway
Summary: S10 AU, set after 10.02: Turned into a demon, Dean pretty much behaves like the monsters he once hunted. But Sam doesn't give up his hope, and after catching him, he tries his best to get his brother back. But he has to face the hard truth: Dean's never coming down from his demonic high again. Is the angel with his fading grace maybe his only chance? [Dean/Cas]
1. Chapter 1

**When Everything Turns To Black**

**Chapter 1**

_When everything turns to black,_  
_you don't know where to go._  
_You need something to justify your soul._  
_Silence is broken, confidence is gone._  
_When everything you're holding on to falls._

* * *

»Yeah, Cas, I got him. Just head to the bunker, okay? I'll see you there.« Although he kept his voice lowered, he knew Dean was able to understand every word he said. He could see him staring at him when he looked into the mirror, but he tended to ignore it. This just wasn't Dean. Every movement, every word of his screamed _Not Dean_. Maybe it was his own soul wandering around in his own meatsuit, but his behavior changed completely, and made him into something unpredictable.

»You're looking for someone to have your back,« Dean summarized the whole call, as Sam finally put his phone down. »Oh yeah, I forgot. It was usually me who had your back.«

Sam shot him a look through the mirror, before his attention strolled back to the dark highway in front of him. Right after Dean had told him he wouldn't took mercy on him either, he prefered to not talk to him again. The real human Dean would never have said something like this to his brother. It was difficult to deal with him now.

»Well, I don't think Cas is a good option as backup. With his stolen grace-«

»What, Dean?« Sam finally said without paying him any more attention other than talking to him. »You want to kill him, too? Rip his angelic throat out?« He had a reason to use Deans own words against him. Maybe Dean would get the hint.

»As far as I'm concerned, there's not much of an angelic throat left.« Dean was well aware of the fact that Cas's grace was burning out. And once it was completely gone, Cas was so as well. Right now, Dean couldn't have cared less about him. »He's gonna die. It's just a matter of time. As it is with you, Sammy.«

Sam stayed quiet. So many thoughts ran through his mind, but right now he couldn't think of one word that would make his demonic brother shut up. Saying nothing was far more intelligent.

They weren't exactly somewhere around Kansas, so it would take much more hours until they would finally reach Lebanon. He had no idea where Cas was, but Sam hoped he would make it to the bunker quick. In front of Dean, he wasn't able to say it, but he could really use Cas's help with Dean at the moment since he had no idea how to deal with him any longer.

Dean was handcuffed to the door in the backseat of the Impala. Without his demonic mojo, he wasn't able to just zap out of here. If he even was capable of doing such things. Sam had no idea, how strong Dean had become. Was he just a regular demon? Apparently not. Even Crowley was afraid to get murdered by the older Winchester which was why he took the blade. Sam could only hope he would throw the thing into a vulcano or toss it onto the moon. Some place safe where Dean wouldn't be able to reach it. It only made him far more aggressive and dangerous as he was even now.

»You're really going to regret the things you've said when you're human again, Dean.«

»When I'm human again?« Dean repeated, a grin slowly appearing on his face. »You're so profoundly convinced that you can turn me back into a human.« He chuckled. »Here I am thinking this couldn't get any better, but it can, right, Sammy?« Dean watched him through the mirror as Sam decided to just stay silent. Again, he smiled. »This is gonna be a long drive.« His voice sounded almost amusingly.

Sam sighed silently.

* * *

»Castiel, where are you going?« Hannah followed Castiel across the playground where the portal to heaven was located right now. The odd angel, the old woman, still sat on the bench, observing them suspiciously.

»I have to go to a place in Kansas. You can either stay here, or come with me. It's your choice.« Castiel stopped, looking at Hannah. Whether she decided to come with him or not, he had to go to the bunker. He was weak, yes, but Sam's call was urgent. He'd found Dean, and in all his demonic glory, he wouldn't be as loving and caring as he used to be as a human. They never talked about it, though it hadn't been necessary to do so. But even without talking about it Cas knew they had to do something. Anything.

Due to the men of letters, they knew how to cure demons. Sure, they'd never finished the ritual before, but they almost cured Crowley. The king was still a demon, however, it left behind a pretty decent impact on him. Maybe they were able to completely cure Dean. Well, it was the only hope Castiel got, and it was worth a shot.

»Let me guess,« Hannah began slowly. »The Winchesters again.«

»Hannah, I... They're my friends and they're in trouble. They need me. I'm so sorry.« Castiel really felt sorry, but regardless of what had happened, he just had to go. Still, Hannah didn't seem to understand. She was angry.

»Just once, you have to think about yourself, Castiel! We have to do something about your Grace. _I'm_ trying to do something.«

»I know,« Castiel interrupted her, not knowing how he could finally bring an end to this discussion. He felt tired. Tired of telling her again, and again that he'd accepted his fate. Even he deserved to die after all he'd been through. Metatron was imprisoned, and they had no clue how to open the gates of Heaven again.

Hannah sensed something wasn't right, and instantly, she calmed down, an apologizing look on her face.

»I'm sorry, Castiel,« she whispered. For a few seconds, she was deep in thought, before she gave up and sighed. »I should come with you. You can't even drive. You probably wouldn't arrive safely.«

Castiel formed a little smile on his face, thanking her without saying a word. He really appreciated her decision.

Hannah pulled the keys out of her jacked to unlock the car, before getting inside, Cas right beside her on the passenger's seat.

»Where do we have to go?« Hannah asked, starting the engine. Maybe she wasn't the best driver, but for an angel who'd only driven a car once in her life, she wasn't that bad either. Angels were quick learners.

»Lebanon, Kansas,« Castiel answered. He sunk a bit into the seat, fully relaxing his body. It seemed like he'd lost a lot of power again. »Just wake me up when we're in Lebanon.« Quickly after the car started rolling, Castiel fell asleep, trying to gain a bit of his power back which he needed so desperately.

The road was almost empty which gave Hannah the opportunity to watch Castiel. His face wasn't even relaxed. He looked lost, and in pain, barely holding it together. Although Sam and Dean themself seemed to have enough problems to deal with at the very moment, Hannah really hoped just one of them would be able to help, or even fix Castiel. She certainly couldn't as she was just an ordinary angel without much of her power.

Metatron would be her backup plan, nonetheless.

* * *

Hannah woke Castiel up after she'd passed the city-limit sign of Lebanon. It took him a few seconds to realize where he was and what had happend, but then he was able to navigate her to the bunker.

The road was as empty as expected, and the Impala was nowhere to be seen. Seemed like Sam was still on the road.

Castiel took advantage of the moment, and got out of the car to get some fresh air. He wasn't feeling any better. Still, he tried to hide this fact, even though Hannah was well aware of his physical state. She watched him as she also got out of the car, leaning against the door after she slammed it close.

Since Castiel had no key to the bunker, and wasn't able to zap anywhere, they had to wait for Sam outside. Both of them stayed quiet. Castiel tired. Hannah not really sure if all this was a good idea. She was still convinced, finding a way to restore Castiel's grace was a much better idea than helping Sam and Dean Winchester, not really sure if one of them could even help Castiel out of his misery. Not losing hope seemed like a real task these days.

* * *

The drive was long and quiet. Sam managed to not speak any more words with Dean who was still sitting in the backseat of the Impala. He only stopped once at a gas station to refuel the Impala, and getting some fresh air without the sharp looks of his brother. The demon inside of him really drove him crazy, and sometimes Sam wasn't even sure what was better: Dean saying all kinds of awful things to hurt him, or Dean staying completely quiet, and just giving him those evil smiles or grins when their eyes met unintentionally in the rearview mirror.

Somehow, he felt really relieved when he finally reached the bunker, and saw another car parked in front of the main entrance. Another person was with Castiel, and Sam identified her as Hannah, the angel who apparently followed Castiel. At least, he wasn't alone in his condition.

»Oh look, my saving angel is here,« Dean tauntingly said. A grin appeared on his face again. Sam just ignored his words before parked the Impala right beside Cas's car. Then he opened the door and got out of the car. He shut the door behind him which gave him the safety to talk to Cas and Hannah without Dean being able to listen to every word they spoke.

»Cas,« he said, greeting the weak looking angel who just raised his hand to greet him back. Then Castiel shot a look forward to the Impala. Through the windows, he could see Dean.

»He seems calm now.«

»He ist calm,« Sam agreed, then he shook his head. »I didn't know how long he would be this calm, so I cuffed him to the door.«

Castiel raised an eyebrow.

»Did he try to attack you?«

»No,« Sam instantly replied, shaking his head slightly. »But trust me, you don't want to get into a fight with him. He's strong. I saw him fight with an ex marine, and he was just playing like it was nothing. He could've killed him within seconds.«

»But he didn't,« Castiel summarized his words and heard Sam sighing quietly.

»Don't get too excited,« Sam said. »I don't even know if there's anything of his former humanity left in him.«

»I can sense it,« Hannah suddenly said, watching Dean for a few seconds before she eyed Sam and Castiel. »Your brother really is strong. A very... dark presence. If I didn't know him, I would think he's a high level demon even angels can't kill.«

»Great,« Sam said unimpressed. »Alright. We should get him inside and lock him in the dungeon. Just... Don't get influenced by what he might say, okay?« He mostly addressed Cas with his words since Hannah had no weak spot Dean could make use of.

Castiel just nodded and watched Sam turn around. Together, they headed towards the car. Dean, still inside, watched every step they took with his green eyes. He didn't give a shit about the female angel, and even Sam was very uninteresting now. Instead, he only focused Castiel. For the first time, he could see his true form. It was just like a silhouette, a shadow even, because even Dean was able to sense his fading, stolen grace. There were no wings at all. Not even broken ones like Hannah seemed to have, even though this image was a bit blurred for a demon. Dean blinked, like he wanted to clear his view, but the next second he wasn't even able to see Hannah's wings again.

Sam opened the car slowly so that Dean had to follow this movement as he was still cuffed to the door. Without letting his older brother out of his sight, he loosened the handcuffs, just to put them back on both of Dean's wrists as soon as the chain wasn't around the door handle.

»Come on,« Sam said, pulling at the chain to get Dean back into movement, and get him out of the Impala. He even followed him, eyes still on Cas.

»Good to see you, Cas,« Dean said amusingly while he was pushed towards the entrance of the bunker. Castiel and Hannah followed anyway.

»I wish I could say the same thing about you,« Castiel replied as Sam opened the door with the key he got from his grandfather.

»Oh, Cas, now you're disappointing me.« Dean didn't sound as disappointed as he said he was, though. For the first time, his eyes wandered to Hannah. »I see you got yourself a little girlfriend. How sweet.«

»We are not-« Hannah realized only a second later that she really wasn't supposed to say or deny anything. Dean probably wouldn't even care at all. And he really didn't.

Sam shot Cas a look as he opened the door, then he pushed Dean inside. Almost as calm as the normal Dean, he went down the stairs, taking in a deep breath.

»Ah, finally back home.«

»Don't get used to the feeling of being around familiar places. You're not going to stay here,« Sam said, as he was shoving his brother towards a certain room.

»Let me guess! The dungeon.« Dean smiled, as if he didn't care. He even chuckled a bit, but he could smile as much as he wanted. Sam knew he was gonna snap eventually. Even Crowley had had a hard time in that dungeon, cuffed to a chair without being able to move one muscle, sitting in the dark with no one to talk to.

Regardless of what Dean said or wanted, Sam felt it was the best to leave his brother there. It was safe for him in the bunker, however, he wasn't sure if there was anything that could've harmed Dean at all. And it was safer for everyone else. Dean seemed to be on edge. Maybe he was as calm as he could possibly get at this moment, but the footage he had viewed in this police station showed very clearly that this state of calm could change within seconds into bloodlust and anger.

Dean headed towards room 7B all by himself to everyone's surprised. Sam followed, and found Dean waiting in front of the large book shelves, standing inside room 7B which was used as kind of archive for all kinds of documents. After he opened the entrance to the bunker right behind the archive, Dean went in, but he stopped right in front of the devil's trap. Only after a little push from Sam, he chuckled, before he finally stepped inside the trap. Even though he didn't want to show it, Sam knew, his brother wanted to avoid the devil's trap at all cost. But there was no way he was going to rest his bones outside of the trap.

There was still a chair in the middle of the huge trap where once Crowley spent his days. The grin was long disappeared from Dean's face, and Sam got the feeling that his brother was going to be pissed eventually. He sat down on the chair anyway, so that Sam could tie him to a chair. In the background, Castiel and Hannah were watching.

»You can't leave me in here forever,« Dean slowly said while Sam tied even his legs to the chair. Then he got up again, looking at his now immobilized brother.

»Not forever,« he corrected him. »Only until we fixed you.«

»Fix me?« Dean repeated, now smiling his amusingly smile again. »There's nothing to fix, Sam. In fact, I feel better than I ever have.«

»Is this you or the demon talking?«

»There is only me.« Dean bared his teeth. A very obvious sign he was going to get angry. »Why can't you accept the fact that I'd rather stay _this_ than going back to be the old, damaged Dean? Oh, is it because I was the one who tricked you into letting an angel in? Now you wanna ruin all the fun I have?«

»You had your fun, Dean.« Sam shook his head slightly, before stepping back out of the devil's trap. His eyes still on his brother. »To me, looking for your dead, missing brother who ran away with the king of hell wasn't fun!«

»Oh, jealousy, Sammy,« Dean throw out. »Is it only because of Crowley? I told you to let me go!« His voice got louder with his last words.

»You were dead, Dean, and in the next moment your body was gone. What was I supposed to think? Oh, he's gone, but it doesn't matter, because he's dead anyway?« Sam turned up the volume as well. But it didn't seem to bother Dean. He was just chuckling again while he just watched his little brother becoming more, and more enraged about his words.

»For instance.« Dean grinned, and Sam seemed like he couldn't take it anymore. Somehow, Dean noticed his anger and frustration. »You could've just let me live my own life. For the first time in my life without having to babysit your annoying little ass.«

The anger just built up in Sam, and Castiel sensed it. He knew the Winchesters too long for not sensing something like that.

»Sam,« he said calmingly, trying to get Sam's focus back to far more important things. Like setting up the ritual which would hopefully cure Dean from being a demon. But Sam refused to listen to him. Instead, he was still watching his brother. And Dean took his chance again to provoke Sam's anger.

»Dad was right. I should've killed you when I had the chance.«

His words were just enough, and Sam snapped. Quickly, he was back inside the devil's trap again, before he just hit Dean right in the face. A groan of pain escaped the demon's lips, blood dripping down his nose. Even his lip was bruised. Sam rose his hand again for another hit, but suddenly Castiel stopped him.

»Enough,« the angel decided, pushing Sam out of the devil's trap, and back to the book shelf. As Castiel shot the demon another look, he could see that his bruised lip had gone back to normal and even the blood flow stopped.

»You're gonna burn for that, Sammy, you hear me?« Dean promised angrily with a rough voice, but Sam just slammed the door behind him, after he'd escaped room 7B.

Castiel shook his head slightly, watching Dean for a few seconds, but then he turned around as well, leaving the room. Together with Hannah, he pushed the book shelves back to it's usual place, closing the dungeon. A few seconds later, Dean could hear the door shutting somewhere behind the shelves, before even the light went out.

Growling silently, he tried to get rid of the ropes around his wrists, but they were far to tight to escape. So he had to wait - something Dean Winchester pissed off even more.

* * *

_**A/N:** As you may have guessed, this is set right after 10.02 »Reichenbach«, and is pretty much my own version of how I imagine season 10 from this point on. Later on, there will be some Destiel. And a lot of demon!Dean of course, because I just love Dean as a demon. It's pretty awesome writing him this way. _

_Furthermore, English isn't my first language, so forgive me if you can find any mistakes. It's not my first english fanfic, but I'm trying to get better. My first language is German, by the way. But writing Supernatural fanfics in German just doesn't feel right. The characters would just sound... awkward since I'm watching the series only in English. _

_Chapters should be coming regularly. _

_I really hope you've enjoyed reading. Let me know what you think! I'll love you to pieces. _


	2. Chapter 2

**When Everything Turns To Black**

**Chapter 2**

_Can you stand the pain?_  
_How long will you hide your face?_  
_How long will you be afraid?_  
_Are you afraid?_  
_How long will you play this game?_  
_Will you fight or will you walk away?_  
_How long will you let it burn?  
Let it burn._

* * *

»You sure about this, Sam?« Castiel asked slowly, watching the Winchester who just stuck his nose into a big old book.

They sat in the library. Hannah investigated the books in the shelves with quiet an interest, while Castiel just sat in a chair. He even got a cup of tea. As if this was going to help him with his real problem.

They did a little digging for the past couple of hours. Even though Dean was locked inside the dungeon, Sam accepted to help Cas with his fading grace. But so far, they got nothing. Sam seemed stressed while Hannah was pretty enthusiastic about all this now that they got help. Just Castiel wasn't that excited. He felt even weaker than one day ago. He'd slept the whole night in one of the many bedrooms the bunker had to offer. It was good, but he didn't exactly feel rested. Not the bed to blame, but his stolen and dying grace.

»Well, we could try it. I don't know if I translated it correctly, because the ritual was written down in a dead language, but it's worth a shot,« Sam explained. Castiel tried to smile, but it felt so fake that he didn't bother trying at all.

»And what if this is not going to work?« Hannah turned around, quite a number of books in her arms. She was worried, Castiel knew that. Sam sensed it, too, but he didn't really have an answer to that. So he just sighed and stayed quiet.

»What do you think, Cas, how much time do you have left?«

Castiel shrugged, thinking about it. Then he said, »I don't know, Sam. Days. Maybe a week.« It was hard to say that exactly. His grace could last for a week if he wasn't using his powers again. Just healing a wound would weaken him pretty fast.

»You should get some rest. I will get all the ingredients, and then we will be doing the ritual.« It was a ritual to find the rest of Castiel's own grace. According to Metatron, there was still a bit left. But he wouldn't tell him until he got free. Letting Metatron out of the cage in heaven wasn't an option, so they had to track his grace by themselves.

Castiel nodded slowly. After taking a sip from his tea, he watched Sam closing the book.

»What about Dean? You haven't looked after him since we locked him up back there.« As a matter of fact, right after Sam had hit Dean in the face, he never entered the dungeon again.

»I'm pretty sure he's still alive,« he answered, before he got up to shove the books back to its usual place in the shelf.

»We should decide, what we'll do with him. Dean was right, Sam, we can't lock him up there forever.«

»I know.« Sam already knew what to do. They knew how to cure demons, and they should use the ritual on Dean. His brother was not going to like it, though.

He could only hope that the ritual would not only cure him, but also clear his mind.

Before getting back to the table, Sam got something out of his duffle, before unrolling the little folder onto the table. Inside, there were multiple syringes, all filled with dark, almost black looking blood. Sam had already filled them with his blood last night, but wanted to wait until Castiel and Hannah were up.

»The ritual has to be held on holy ground, so we have to bless the dungeon first.« Using the bunker with its large devil's trap on the ground seemed to be a lot easier to use, than dragging Dean's ass to a church. The danger to have him escaping was quite higher with Dean than it had been with Crowley.

»It's alright, I can do it,« Hannah offered. She went back to the table to place all the books in her arms on it. Sam nodded slightly. He really appreciated Hannah doing this since she was only here for Castiel. At the end of the day, she was an angel anyway, so it seemed to be a lot wiser to let her do this. Cas was too weak. He should spare his powers.

»When do you want to start?« Castiel asked, watching Sam with a somewhat sad look on his face. It was as hard for him to see Dean in a situation like this, as it was for Sam. They just had to act through the pain. To function, like they always had.

»Today. Right after Hannah is done blessing the dungeon. I really don't want to wait any longer.« That was his brother in there, and they had to do something about it. Being a demon wasn't an option. It never would be.

»I can start immediately, I just need a bit of holy water,« Hannah broke the upcoming silence, and Sam jumped in his chair.

»Yes! Yeah, I think I got some in the trunk of the car. I'll go get it!« Without waiting any longer, he got up, leaving the library, and escaping somewhere through the strategy room. He'd parked the Impala in the garage with all the other vintage cars.

Cas leaned back in his chair while he was watched by Hannah.

»How do you feel?« she asked in a worrying tone. Hannah somehow had the feeling that Cas had lied earlier. He probably knew, he wouldn't have a week long until his grace would be completely vanished.

»I'm fine,« Castiel still insisted. »I'll feel better when Dean isn't a demon anymore.« He was just being honest, but Hannah shook her head slowly, a sad smile on her face.

»You just have to think about anyone else, before you finally start to worry about yourself, am I right?«

»It's not like that,« Cas said. »Dean was always my responsibility. I rescued him from hell, and now he's back in hell.«

»He's not back in hell, Castiel. He's still here on earth, alive.«

»He's a demon, Hannah, which is even worse. I saved him from facing eternity in hell, and maybe even slowly turning into a demon. I should have known the mark wasn't any good.« Castiel thought that part of it all was his fault. He knew about the story about Cain and Abel. Every angel did. But still, he was naive and full of good hope, without thinking about the consequences. He should have done something about it when he had the chance. Now it was too late.

»It's not your fault, Castiel. We will fix him.« She tried to smile, to lighten up his mood, when suddenly Sam came back to the library. A flask with holy water in his hands.

The look on his face made clear that that he'd listened to the conversation. After giving Hannah the flask, Sam's eyes met Castiel's.

»She's right, Cas. It's not your fault,« he slowly said. »If anyone's to blame, that would be me. I told him to leave, and that led him right into Crowley's arms.«

»I was with you that night, Sam.« Castiel shook his head, sighing quietly. Hannah just stood by, watching the two of them, in pain over Dean's dark side. Maybe she wasn't around when all those events occurred, but she knew that none of this was their fault. Dean obviously got the Mark of Cain all by himself, and with a clear mind. The only one who was to blame was Dean himself.

After a few long minutes, she felt pretty uncomfortable, and wanted to escape the silence, so she looked down at the flask.

»I will go and bless the dungeon now. It won't take long, just a few minutes,« she explained. Normally, she would be done after just a few seconds, but she wanted to do it right. The older Winchester seemed quite important, and Hannah didn't want to be the one to make any mistakes and ruin the ritual.

»Alright,« Sam said, finally looking at her again. »Just don't let Dean bother you. Ignore him.«

»Don't worry, I can handle his attitude.« She smiled slightly, then she left the library to head to room 7B.

Without making much noises, Hannah entered the room, and shoved the bookshelves aside. The light was turned on, revealing Dean calmly sitting in the middle of this huge devil's trap, watching his new guest.

»Look who we got here,« he said with a cocky grin.«Cas's girlfriend. Shouldn't you be worried about your sweetheart?«

Hannah tried to ignore his words. He was still tied to a chair, unable to move. He just had his mouth, and that he was going to use obviously.

Without reacting to him or his words, Hannah stepped inside the trap, opening the flask in her hands. Slowly, she poured the holy water onto the ground, murmuring a blessing under Dean's sharp looks.

Dean already knew why Hannah was blessing the ground. Sammy obviously didn't want to drag him to an abandoned church, so he wanted to do the ritual here. Either way, he wouldn't stop until Dean was human again. He hated this fact, and his anger built up. Even more so than it already did these past hours. He felt the urge to kill, and he probably would have killed Hannah if he had a chance to lose the cuffs.

Hannah closed the now empty flask, eventually shooting Dean a look. She wasn't surprised to feel the anger building up inside him. She could sense that as an angel with still most of her grace left. The first time she'd met him, she'd felt almost as much pain, sorrow, and anger as she did now. Now there was only one emotion left: anger. And bloodlust. Like he was starving, but not longing for food, but for killings. It made him almost unpredictable.

Dean watched her, smiling a bit as their eyes met. Even though Hannah wanted to take Sam's advice, she still had something to say.

»Don't worry, you'll be human again in just a few hours.«

»Oh, I doubt that, sweetheart,« Dean said totally convinced.

»There's no other way. The things you did... I don't understand why you want to be a demon.« Hannah shook her head, observing him like he was some sort of new animal. Well, an animal, he was. Castiel had told her what Dean had done. How he'd behaved for the past couple of weeks, even before his death.

»You're right,« Dean agreed. »You don't understand.« His voice was completely calm, almost amused. But Hannah knew this was just a trick, because she could sense it. How he was barely holding up. Maybe it was wise to start the ritual as soon as possible.

Without any other words, Hannah turned around, and left the dungeon. She found Sam and Castiel still sitting in the library.

»I'm finished,« Hannah announced and two heads turned towards her. Sam just nodded thankfully.

»So, how's he doing?« he asked slowly. A little sigh escaped Hannah's lips.

»He's angry,« she began, thinking about the emotions she was able to sense as an angel. »Not just angry, but _hungry_. He'd tried to stifle his feelings, but I could sense his aggressiveness quite clearly.«

»It's probably the mark,« Castiel guessed, and Sam shot him a look.

»The mark? You mean, the Mark of Cain is still influencing him?« Sam thought, with Dean's death, the mark would lose its influence on him since he wasn't human anymore. Apparently, he was wrong.

»The mark won't let go of his owner, human or not. I'm sure he'd used the First Blade all the time. That left a pretty decent impact on him. He's used to the feelings the blade gave him. Power, like playing god.« Castiel got out of his chair, still feeling not so good. »We should start immediately. The sooner he's healed, the better.«

»You're right,« Sam agreed. To be honest, he wasn't so sure about all this. Was he doing the right thing? And what if Dean wasn't curable? Right now, he really couldn't think about all this. He was his brother. The most important person in his life.

* * *

Sam felt pretty bad as they were heading towards the dungeon. Even though only his own brother was waiting inside, he still had no idea what was actually waiting for him. They had no idea if the ritual was going to work. He knew, they had no time for second thoughts, but he couldn't help but thinking about the possibility that Dean couldn't be cured at all.

Castiel pushed the bookshelves open, his eyes immediately on Dean. Dean instead looked right over at Sam.

»Long time no see, Sammy,« he joked with a slight grin on his face.

Sam said not a single word, as he unrolled the folder with all the syringes.

»Ah, human blood. I hope it's still warm. I don't like cold blood running through my veins.«

»Really? You're dead, so there shouldn't be any warm blood left in that dead body of yours.« Sam shot his brother a look. Dean seemed to be slightly impressed by this answer, but then he laughed eventually.

Sam took one of the blood-filled syringes in his right hand, stalling.

»Sam, I can-,« Castiel began, watching him, but Sam cut him off.

»No, it's fine. I can do it.« He kept his voice lowered, so that Dean wasn't able to hear him. It was better this way.

Finally, he turned towards Dean and as he came closer, Dean started to flex his muscles and to grit his teeth a bit, just like an attack dog. Sam tried to work fast, and as the needle entered Deans neck, he growled, part of in pain, part of anger. The blood shot through his veins, getting in every inch of his body, as the ritual started.

»You really think those are gonna work? Let me tell you something, Sam, I'm not a regular demon.« Dean still had to fight with the influence of the human blood inside his body. Sam stepped away from him, just to be sure.

»I know you are a demon. Cain became a Damon as well.«

»Try knight of hell,« Dean interrupted, gritting his teeth again as Sam watched him surprised. Castiel shot the younger Winchester a look, but then he came closer to Dean.

»It doesn't matter. We'll still be doing the ritual. You can't stay like this.« The angel shook his head, watching Dean's normally green eyes switch to black, revealing the demonic presence inside. Even though Castiel had lost most of his angelic powers, he could still feel the anger building up in Dean. The black eyes showed that he wasn't joking anymore. That beast inside wanted to get out, just like an animal in a cage. If he only could…

»Oh, we'll see, Cas,« Dean promised. »You're lucky I'm trapped in here. I could snap your neck like it is nothing. You might know I can sense that you're just an inch away from being human. From being _dead_.«

Castiel preferred to not listen to him. He turned away to face Sam and Hannah, both looking very troubled. Behind him, he could hear Dean growl.

»One hour, Cas. We should let him alone and come back in an hour to give him the next injection,« Sam suggested, but the angel shook his head.

»You can go, I'll stay.« This was maybe the last chance for him to spend time with Dean, and to talk to him. He wanted to use it wisely by not sitting in the library, waiting for the next injection.

First, Sam didn't know whether this was a good idea or not, but then he agreed. Turning to Hannah, he sighed, gesturing her to leave the room with him together. Only after forcing her to move, she was willing to leave Cas and Dean behind. It just wasn't a good idea.

Castiel waited for the door to shut close behind them, then he slowly turned towards Dean, facing the pure evil inside him.

»Why did you run away, Dean? We could've helped you sooner.«

»I already said it before, I don't want you to help me. I'm not sick. In fact, I'm feeling pretty good,« Dean replied. His eyes went back to its normal color again. Again, he tried to free his arms, then he looked at Castiel. »Come on, Cas, let me out of here.« He was already tired of this cuffs on his wrists, and not be able to move even the slightest bit. Castiel only shook his head, which made him even angrier.

»You know I can't do that. Not before we have finished the ritual.« Not before he was human again.

Watching him, Castiel saw Dean flex his muscles. Then he leaned back, almost as if he was starting to relax.

»I could help you,« the Winchester offered. »You know, even if you get the remaining rest of your own grace back, it can already be too late. You're weak. And you need someone to restore your grace so that it won't burn out.«

His words made Cas raise his eyebrows.

»And you could help me with that?« Castiel finished his words, and the demon nodded, a slight grin appearing on his face.

»Don't forget how much power I gained. Being a knight of hell, with the Mark of Cain. Crowley by my side. I could practically make whole hell go after your grace. Let them find a way to give you as much power to survive.«

Castiel thought about it for a moment. Getting his own grace back seemed like the only way to survive without hurting any other angel again. Thinking about it further, it could also be the only chance for Dean to get free. The chance that the older Winchester could simply trick him into believing he could help him was too risky. Dean was smart. And the demon in him seemed to be even smarter. Should he really risk it?

»If I let you out of here, you would disappear without saying a word,« Castiel slowly said, and Dean smiled a bit. »I can't trust you.«

»Well,« Dean said shrugging. »It's not my life that's going to end.«

These words were enough to let Castiel think about his offer again. Was he really able to help? And what part would Crowley play in all this? The king of hell had probably long recognized that Dean was missing. Castiel wasn't sure if he would help him as well.

Thinking about it for a few minutes, Cas decided that it was worth a shot. Dean might be stronger than him, but maybe there was something of his humanity left so that Dean won't be killing him. No, Castiel was sure about one fact: Dean wouldn't kill him.

»Alright,« Castiel decided, turning away to find a knive. Coming closer to Dean, he saw him smiling again.

»Hurry up,« the demon demanded, watching the angel cutting the ropes around his arms, his wrists, and his ankles. Finally, he was able to move, and he got up. His wrists were bruised a little and the demonic handcuffs still bothered him, but after shooting the angel a look, Castiel shook his head.

»I'm sorry, but as long as I can't trust you, you have to live with the cuffs.«

Dean growled, then he nodded.

»Fine,« he said, »now get me out of here!«

* * *

Sam watched the clock nervously. Five minutes more and Dean would get the next injection. He wondered, how he would react to the second dose of human blood. Probably not better than to the last one.

»What do you think they're talking about?« Hannah suddenly asked, breaking the silence. Sam shrugged, then he sighed.

»Dean is probably trying to scare him away. And Cas… probably as calm as ever.« In fact, Sam was sure that Cas wouldn't really care about the things Dean said. Even though he'd never seen him in such a bad shape before. But Castiel was strong, even if his body was not.

»This ritual you talked about earlier… Can you really track down Castiel's grace with it?« Hannah's voice was shivering a bit. She really did care about Cas.

»I don't know. I hope so,« Sam answered honestly, watching her. Hannah nodded slowly, then shooting him a look, trying to smile a little.

»I only wish I could do more for him.«

»I know, but Hannah… We'll find a way, okay? I'm sure if Dean's Dean again, he'll help us too.« Which meant, they had to cure his brother first. But once he was him again, he would do everything he could to help their angel.

Hannah smiled again, then she got up.

»I think it's time.«

Sam checked his watch, then he got up too. Heading towards room 7B, he imagined what it'd be like in the dungeon now. Was Dean calm? Or were those two fighting?

After opening the door and shoving the shelves to its sides, he instantly saw that something wasn't right. The devil's trap was empty, so as the chair. Dean was gone, but more importantly, Cas was gone as well.

»What the…« Sam turned around only to find Hannah as speechless as himself. »They're both gone.«

* * *

**A/N:** _Thanks for following and favoriting! Let me know what you think! __  
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